New to forum so please move if in wrong place. I’ve had this oil seep forever now on bell housing and it just got worse I have no idea where it’s coming from, I checked inspection on trans and it was dry I have no idea where it’s coming from. Don’t know where to check etc. anyone please help...

I have an 2007 classic duramax that I noticed oil accumulated on top of the motor under the Y pipe turbo area. I understand some EGR leakage can form mists of oil in this area but wonders if I am looking at something different with it being about 1/2 inches deep in the low areas. Thanks for any...